Transformation example
Is there a way for me to use a transformation like this to use as an inner query in 'table input 4' like using 'insert data from the step' or 'execute sql script'? If not, is my only option using the whole query in the table input step?
Related
I'm using a PostgreSQL with a Go driver. Sometimes I need to query not existing fields, just to check - maybe something exists in a DB. Before querying I can't tell whether that field exists. Example:
where size=10 or length=10
By default I get an error column "length" does not exist, however, the size column could exist and I could get some results.
Is it possible to handle such cases to return what is possible?
EDIT:
Yes, I could get all the existing columns first. But the initial queries can be rather complex and not created by me directly, I can only modify them.
That means the query can be simple like the previous example and can be much more complex like this:
WHERE size=10 OR (length=10 AND n='example') OR (c BETWEEN 1 and 5 AND p='Mars')
If missing columns are length and c - does that mean I have to parse the SQL, split it by OR (or other operators), check every part of the query, then remove any part with missing columns - and in the end to generate a new SQL query?
Any easier way?
I would try to check within information schema first
"select column_name from INFORMATION_SCHEMA.COLUMNS where table_name ='table_name';"
And then based on result do query
Why don't you get a list of columns that are in the table first? Like this
select column_name
from information_schema.columns
where table_name = 'table_name' and (column_name = 'size' or column_name = 'length');
The result will be the columns that exist.
There is no way to do what you want, except for constructing an SQL string from the list of available columns, which can be got by querying information_schema.columns.
SQL statements are parsed before they are executed, and there is no conditional compilation or no short-circuiting, so you get an error if a non-existing column is referenced.
I would like to create a job than based on some values in Table A, execute a Select query in Table B where the WHERE CONDITION must be parametric.
For example: I have 10 columns in A with 100 rows filled. 9 of my columns can be nullable so I have to create a query that controls the nullability of a value, if null then it must NOT be considered a research criteria in the Select statement.
I thought about using a SPARSE lookup where I'd pass a string that I created with the concatenation of the research parameters if they're not null but the job fails because you need to map the columns.
I even created a file with queries as string and then I loop the file and pass the string as a variable for the DB2 connector stage. It works... but I have more than 10000 rows means 10000 queries.. not that fast.
Thanks for your help.
PS: I'm new to this stuff :D
what you can do is to use Before SQL option at your source/target stage. Namely, your job will have at least two stages. One source db2 stage and one copy or sequential or peek stage as target or Row generator and target db2 connector.
In your input db2 connector you can pass your sql script as parameter into before sql provided that it is generated in advance and pass it as value to your before sql of db2 connector. Your actual sql statement will use "dummy" script such as "select current date from sysibm.sysdummy1" to complete your execution.
Hope it makes sense.
For example, I'd like to run:
REGEXP_REPLACE("What's My Name?", "[^a-z0-9_\-]", "-");
and simply see what it returns, instead of doing a search against a DB Table. I tried to run it in the CLI and got
ERROR: syntax error at or near "REGEXP_REPLACE"
LINE 1: REGEXP_REPLACE("What's My Name?", "[^a-z0-9_\-]", "-")
(I'm trying to be generic- I'd like to be able to use this for other PSQL Aggregate Functions as well.)
Remember, this is SQL, so every output you get is a relation. Hence to calculate the result of a function, you need to run SELECT to retrieve the function's value.
Unfortunately, in many DBs, SELECT requires a table. In Oracle land, there's dual to work around this problem:
SELECT REGEXP_REPLACE('What''s My Name?', '[^a-z0-9_\-]', '-') FROM dual;
PostgreSQL, however, allows you to execute a SELECT query without having to specify a table:
SELECT REGEXP_REPLACE('What''s My Name?', '[^a-z0-9_\-]', '-');
Note that the string quote in SQL is ', not ". PostgreSQL uses double quotes to quote identifiers.
Side note: Not every function is an aggregate. An aggregate is a function that combines multiple values into a single output value. REGEXP_REPLACE() is just a normal string function.
Is there a way to run a single PSQL Aggregate Function without hitting a database table?
Yes, in PostgreSQL you can write a SELECT statement without a FROM part at all.
how to get data from a specific column in fire bird? something like.
select from rdb$relation_fields
where rdb$relation_name = 'table' and rdb$field_name = 'code'
Your question doesn't quite make sense to me - if you already know the table and field name (as you do in your example) then why not select directly from the table? Anyway, you can create SQL statement dynamically in PSQL as string and then execute it using EXECUTE STATEMENT. The EXECUTE BLOCK might also be of intrest, depends where and what exactly youre tring to achieve.
EDIT after reading the comment
So just build the SELECT statement at the client side, selecting the field currently selected in combobox. You don't mention the language you use but generaaly it something like
query.SQL := 'SELECT '+ comboField.Text +' FROM '+curTableName;
query.Open();
// read the resultset
The requirement is to generate a single report connecting to a single DB:
Query1 is a group by query and has a bar chart and pie chart based on it.
Query2 is a simple query on which a table gets created.
Both these queries need results based on a WHERE clause, which is supplied dynamically.
Can somebody point me to some examples on how to achieve this?
Thank you.
You can tell JasperReports to use a parameter to define part of the query using the $P!{PARAMETER_NAME} syntax. This tells JasperReports to use the literal value of PARAMETER_NAME as part of the query. You can then do:
Create a parameter named WHERE_CLAUSE in the report.
Give WHERE_CLAUSE a default value of 1=1.
Consider the following SQL statement:
SELECT * FROM table WHERE $P!{WHERE_CLAUSE}
The $P! expression changes the literal SQL statement to:
SELECT * FROM table WHERE 1=1
That is a valid query. Note the difference between $P{} and $P!{} -- the exclamation mark (!) is important.
You can then supply the SQL conditions dynamically.